Translating presbyopic contact lens

ABSTRACT

Lenses for correcting presbyopia are translating, multifocal contact lenses with pseudotruncations which are asymmetric about the vertical meridian.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a non-provisional application which claims priority to U.S.Provisional Applications 61/386,951, filed Sep. 27, 2010. Theaforementioned application is incorporated in full by reference herein.

BACKGROUND OF THE INVENTION

As people age, their eyes are less able to accommodate, or bend thenatural lens, to focus on objects that are relatively near to theobserver. This condition is known as presbyopia. Contact lenses can beworn to address presbyopia. In one type of such lenses, distance andnear vision regions are concentrically arranged around the geometriccenter of the lens. Light passing through the optical zone of the lensis concentrated and focused at more than one point in the eye.

In another type of lens, a segmented lens, near and distance visionregions are not concentric about the geometric center of the lens. Thewearer of the segmented lenses is able to access the near vision regionof the lens because the lens is constructed to allow it to translate, ormove vertically relative to the pupil of the wearer's eye. The lensmoves vertically when the person wearing the lens shifts their gazedownwardly to read. This upwardly positions the near vision portion inthe center of the wearer's gaze. Substantially all of the light passingthrough the optical zone can be focused at a single point in the eyebased on gaze.

One type of translating lens has a truncated shape. That is, unlike mostlenses that are continuously circular or oval, the lower portion of thetruncated contact lens is flattened by cutting off or shortening thatpart of the lens. This results in a substantially flat, thick edge atthe bottom of the lens. Exemplary descriptions of such lenses includeU.S. Pat. Nos. 7,543,935; 7,430,930; 7,052,132; 4,549,794 incorporatedherein by reference. Unfortunately, a relatively flat edge on contactlenses such as these tends to reduce comfort. It is desirable to have atranslating contact lens with improved comfort.

Another type of translating lens has an outer shape which iscontinuously circular or oval, but contains a substantially thickenedportion peripheral to the central optical zone. This thickened portionis intended to contact the lower lid and translate with blink. Exemplaryreferences to such a lens are described in U.S. Pat. No. 7,040,757 andUS 20100171924, incorporated herein by reference. In these examples, thethickness in the peripheral portions of the lens outside the opticalzone is substantially uniform for meridians parallel to the verticalmeridian of the lens, and a lens according to this invention exhibitsmirror symmetry with respect to a plane cutting through the verticalmeridian.

U.S. Pat. No. 7,216,978 shows that the upper and lower eyelids do notmove strictly in a vertical, with an up and down stroke during blink.The upper lid moves substantially vertical, with a small nasal componentduring blink, and the lower lid moves substantially horizontal, movingnasalward during blink. Additionally, the upper and lower eyelids arenot symmetrical with respect to a plane cutting through the verticalmeridian.

Lens surfaces can be generated using different functions. For example,U.S. Pat. Nos. 3,187,338, and 5,975,694 describe a sine function; U.S.Pat. No. 6,843,563 uses a third order polynomial function, and U.S. Pat.No. 5,650,838 uses a tangent function; in U.S. Pat. No. 6,540,353 a lenssurface is generated using a rapid power change over a small distance inthe optical zone and in U.S. Pat. No. 5,608,471, a rapid transition onthe lens surface is made by a straight linear function.

In U.S. Pat. No. 7,004,585, the distance and near centers of atranslating lens both lie on the vertical bisector of the optical zone.

It would be advantageous to have a contact lens with a feature thatfully engage the lower eyelid of the wearer to facilitate lenstranslation and which provides improved wearing comfort.

SUMMARY OF THE INVENTION

The invention is a translating contact lens comprising features whichare asymmetric about the vertical meridian. In one aspect of theinvention, this feature is a pseudotruncation.

In another aspect of the invention, the pseudotruncation issubstantially below the horizontal meridian of the lens.

In yet another aspect of the invention, the optical zone is asymmetricabout the vertical meridian of the lens.

In yet another aspect of the invention, both the pseudotruncation andoptical zone are asymmetric about the vertical meridian of the lens.

In yet another aspect of the invention, the pseudotruncation is rotatednasally up and asymmetric about the vertical meridian of the lens.

In yet another aspect of the invention, the pseudotruncation is rotatednasally up by between about 1 to 15 degrees and preferably between about7 to 8 degrees.

In yet another aspect of the invention, the pseudotruncation is rotatednasally down by between about 1 to 10 degrees.

In yet another aspect of the invention, the optical zone is rotationallyaligned with the pseudotruncation.

In yet another aspect of the invention, the optical zone is notrotationally aligned with the pseudotruncation.

In yet another aspect of the invention, the optical zone is insethorizontally nasalward and asymmetric about the vertical meridian of thelens.

In yet another aspect of the invention, the optical zone is rotatednasally up and asymmetric about the vertical meridian of the lens.

In yet a further aspect of the invention, the pseudotruncation iscomprised of more than one elevated zone.

In yet another aspect of the invention, the angular subtense of thepseudotruncation when it is at least about 80% of its maximum thickness,is between about 40 and about 100 degrees.

In yet another aspect of the invention, the pseudotruncation varies inheight or circumferential angular subtense with changes in refractiveprescription.

In yet another aspect of the invention, the radial position of the peakthickness value of the pseudotruncation at any meridian around the lensis substantially constant, the arc being a portion of a concentriccircle about the lens center.

In yet another aspect of the invention, the radial position of the peakthickness value of the pseudotruncation at any meridian around the lensis variable, the arc not being a portion of a concentric circle aboutthe lens center.

In yet another aspect of the invention, the outer circumference of thelens is not circular, and not concentric about the lens center.

In yet a further aspect of the invention, the width of the bevel portionof the pseudotruncation is between about 50 and about 500 microns.

In yet a further aspect of the invention, the position of the bevelflange junction is between about 5 to about 7 mm.

In yet a further aspect of the invention, the maximum radial thicknessat the lenticular bevel junction is between about 300 and about 600microns.

In yet a further aspect of the invention, the maximum radial thicknessat the bevel flange junction is between about 75 and about 250 microns.

In yet a further aspect of the invention, the design of thepseudotruncation is based upon measurements of a population,sub-population or group.

In yet a further aspect of the invention, the design of thepseudotruncation is based upon measurements of a single individual.

In yet a further aspect of the invention, the design of thepseudotruncation is based upon mathematical smoothing functions appliedbetween fixed defined points.

In yet a further aspect of the invention, the design of thepseudotruncation is based upon a mathematical smoothing function basedupon scaling from the value derived from the sin² function appliedbetween fixed defined points.

In yet a further aspect of the invention, the design of thepseudotruncation is based upon a mathematical smoothing function basedupon scaling from the following equation:T ₃ =T ₁+(T ₂ −T ₁)*(Sin((P ₃ −P ₁)/(P ₂ −P ₁)*90))^(n)  Equation 1]wherein P1 is the distance from the lens center to optical lenticularjunction and T1 is the thickness at optical lenticular junction, P2 isthe distance from the lens center to lenticular bevel junction, and T2is the thickness at lenticular junction. P3 and T3 are the arbitrarydistance from the lens center and thickness at an arbitrary position.

In yet a further aspect of the invention, the preferred value of n isbetween about 1.25 and about 4. The more preferred value of n is betweenabout 1.5 and about 2.5. The most preferred value of n is 2.

In yet a further aspect of the invention, the surface of the lens or aportion thereof, is generated by specifying a fixed thickness at twopoints on the lens and then scaling a smooth surface between saidpoints, the scaling using the sine or cosine taken to an exponentialpower between about 1.25 and about 4.

In yet a further aspect of the invention, the surface of the lens or aportion thereof, is generated by specifying a fixed thickness at twopoints on the lens and then scaling a smooth surface between saidpoints, the scaling using the sine or cosine taken to an exponentialpower of about 2.

In yet a further aspect of the invention, a pseudotruncation accordingto this invention comprises an elongated, arcuate thickened portion inthe lens, peripheral to the optical zone but inside of the edge, whereinsaid thickened portion is asymmetrical with the vertical meridian of thelens, and the thickened portion engages with the lower eyelid to achievetranslation on the eye.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the eyelid asymmetry typically found.

FIG. 2 depicts one embodiment of a lens of the invention, in plan view.

FIG. 3 depicts one embodiment of a lens of the invention, shaded forthickness.

FIG. 4 depicts another embodiment of a lens of the invention, in planview.

FIG. 5 depicts one embodiment of a lens of the invention, shaded forthickness.

FIG. 6 depicts yet another embodiment of a lens of the invention, inplan view.

FIG. 7 shows a cross section of the pseudotruncation according to theinvention.

DETAILED DESCRIPTION

The invention provides methods for correcting presbyopia, contact lensesfor such correction, and methods for producing the lenses of theinvention. The lenses of the invention are translating, multifocalcontact lenses with pseudotruncations. The pseudotruncation of theinvention is asymmetric about a vertical meridian of the lens. Thetranslating contact lenses of the invention are lenses without asubstantially flat or straight portion about their outermostcircumference. The circumference may be substantially circular or smoothand continuous; or it may be asymmetric. The lenses of the presentinvention comprise an optical zone, a peripheral pseudotruncationlocated radially outwards from the optical zone, and an edge zonelocated radially outwards from the peripheral zone and encompassing thelens edge.

The “optical zone” is defined as the substantially central portion ofthe lens which contains the visual power correction for the wearer'sametropia and presbyopia. “Ametropia” is defined as the optical powerneeded to provide good visual acuity, generally at far distance. It isrecognized that this would include myopia or hyperopia, and astigmatismconcurrent with either. Presbyopia is corrected by adding algebraicallyplus optical power to a portion of the optical zone to correct thewearer's near visual acuity requirements. It is recognized that theseoptical powers may be created by refractive means, or diffractive means,or both.

The optical zone comprises at least at least one near vision zone andpreferably at least one distance vision zone. Alternatively, the opticalzone has more than one distance vision zone and/or more than one nearvision zone; preferably, one distance vision zone lies substantially ator above the horizontal meridian of the lens and a near vision zone liesat or beneath the horizontal meridian. Optionally, the optical zone ofthe lens has one or more intermediate vision zones. Intermediates visionzones contain a partial or fractional presbyopic add power. The opticalzone may be symmetrical or asymmetrical with respect to the verticalmeridian of the lens. Preferably, it is vertically asymmetrical. The“optical zone” is the combination of distance, near and optionally,intermediate vision zones. The transitions between the distance, nearand optionally intermediate zones may be abrupt and occur over a verysmall distance, as seen in a step power change, or smooth and occur overa larger distance, as in a progressive power change. In a preferredembodiment, the transitions are as abrupt as possible to avoiddiscomfort for the wearer and also to minimize the translation required.

A “distance vision zone” is a zone that provides the distance opticalpower or the amount of refractive power required to correct the lenswearer's distance vision acuity to the desired degree. A “near visionzone” is a zone that provides the near optical power or the amount ofrefractive power required to correct the wearer's near vision acuity tothe desired degree. An “intermediate vision zone” is a zone thatprovides the optical power or the amount of refractive power required tocorrect the wearer's intermediate vision acuity for viewing objectstypically between the wearer's preferred distance and near vision range.A “multi-focal translating contact lens” refers to a translating contactlens that comprises bifocal, trifocal or multi-focal optics.

The “vertical meridian” is defined as a line which runs from theinferior edge of the lens to the superior edge of the lens, through thelens geometric center. The “horizontal meridian” is defined as a linewhich runs from the nasal edge of the lens to the temporal edge of thelens, through the lens geometric center. The “lens center” is found atthe intersection of the horizontal and vertical meridians.

A “pseudotruncation” is a design feature placed on the anterior surfaceof the lens in the peripheral zone surrounding the optical zone andoptical zone junction, that enables a lens having it to translate ormove on the eye as the direction of gaze changes so that distance ornear vision is corrected accordingly. This feature participates in thetranslation of the lens by interacting with the lower eyelid so that asgaze is shifted down, the eyelid causes the lens to move in thedirection of the superior portion of the eye. As the gaze is shifted up,the eyelid causes the lens to move in the direction of the inferiorportion of the eye. Preferably, translation of the lens when the gaze isshifted down occurs due the pushing of the lower eyelid against thepseudotruncation.

A lens with a pseudotruncation according to this invention is nottruncated in its lower portion and preferably is not truncated orflattened anywhere about its circumference. The pseudotruncation for alens according to this invention comprises a lenticular portion, alenticular bevel junction, a bevel portion, a bevel flange junction, anda flange portion, and is asymmetric about the vertical meridian of thelens.

In another embodiment, a pseudotruncation according to this inventioncomprises an elongated, arcuate thickened portion in the lens,peripheral to the optical zone but inside of the edge, wherein saidthickened portion is asymmetrical with the vertical meridian of thelens, and the thickened portion engages with the lower eyelid to achievetranslation on the eye.

“Lenticular portion” is a portion of the lens surface which extendsradially out from center, beginning at the junction at the optical zonelenticular junction and ending at the lenticular bevel junction. “Bevelportion” is a portion of the lens surface which extends radially outfrom center, beginning at the junction at the lenticular bevel junctionand ending at the bevel flange junction. “Flange portion” is a portionof the lens surface which extends radially out from center, beginning atthe bevel flange junction and ending at the lens edge.

“Lenticular bevel junction” is the junction between the lenticular andbevel portions of a lens surface. “Bevel flange junction” is thejunction between the bevel and flange portions of a lens surface.“Radial thickness” is the thickness of a lens as measured from a tangentto the back surface to the front surface at any position on the backsurface. “Optical lenticular junction” is the junction between the nearor distance optical zone and the lenticular portion.

The pseudotruncations described above are generally thickened portionsof the lens (relative to the thickness of the rest of the optical zone)and generally have a steep portion. A substantial portion of thepseudotruncation is preferably below the horizontal meridian of the lens(a diameter running mid-way through the lens from right to left/temporalto nasal or vice versa). More preferably, the thickest portion of thepseudotruncation lies predominantly along the lower one third of lenswith respect to the horizontal meridian and is curved and disposed togenerally coincide in shape with the lower eyelid when in use. Theperipheral most portions of the flange and the lens edge are expected toposition underneath the bottom eyelid, and are preferably as thin aspractical. More preferably they are 150μ or less.

It is also preferable that the pseudotruncation be asymmetric about thevertical meridian of the lens with a bias towards the inferior or nasalportion of the lens. This aids in the interaction of the lens and thelower eyelid. In most cases, the shape or curvature of the upper andlower eyelids are not symmetrical with respect to a plane cuttingthrough the vertical meridian of the eye. Additionally, the upper lidmoves substantially vertical, with a small nasal component during blink,and the lower lid moves substantially horizontal, moving nasalwardduring blink. There are measurable differences between people in theireyelid anatomy, specifically the upper and lower eyelid shapes, and thepalpebral aperture between the two lids. The asymmetric pseudotruncationcan be designed based upon population or sub-group averages or customdesigned for a single wearer.

FIG. 1 depicts major features of a typical right eye, as seen facing thepatient. Vertical pupillary axis 33 bisects the pupil 36 vertically andsimilarly horizontal pupillary axis 34 bisects the pupil horizontally.The pupil center is located at the intersection of the verticalpupillary axis 33 and the horizontal pupillary axis 34. Surrounding thepupil is the iris 35. The upper eyelid margin 31 and the lower eyelidmargin 32 are drawn in a typical presentation. It should be noted thatthe two eyelids are not horizontally tangent to the edge of the pupil36, nor tangent to a line drawn parallel to the horizontal pupillaryaxis 34. The position of the nose is depicted as “N” in FIG. 1.

We have found the eyelids on average, are tilted with respect to theedge of the pupil 36, or tangent to a line drawn parallel to thehorizontal pupillary axis 34. Most commonly, both eyelids are tiltednasally up as depicted in FIG. 1. In a large population sample, we foundthat the average tilt of the upper eyelid margin 31, when the eye isrotated about 30° downward to the reading position is about 5° nasallyup, ranging as high as about 15° nasally up. By “nasally up” is meantthat on the nasal side, the eyelid margin is tilted or rotated higher.In a similar fashion, we found that the average tilt of the lower eyelidmargin 32, when the eye is rotated about 30° downward to the readingposition is about 7° nasally up, ranging as high as about 15° nasallyup.

Since the eyelid margins are tilted and asymmetrical relative to thehorizontal meridian, or a line parallel to it, it is advantageous toconstruct a translating contact lens with asymmetric optics andpseudotruncation which matches the lid position, in order to betterengage the contact lens and enable vertical translation.

In a preferred embodiment, referring to FIG. 2 lens 10 has an anteriorsurface, as shown, and a posterior surface, that is not shown. Theoutermost circumference of lens 10 is symmetrical about the verticalmeridian 110 and lens center 120. Lines 100 and 110 represent thehorizontal, or 0-180 degree, and vertical, or 90-270 degree, meridiansof the lens, respectively. At the intersection of the horizontal 100 andvertical 110 lines is the lens center, 120. On the anterior surface ofthe lens is a distance optical zone 14 and a near optical zone 13, bothending at the optical lenticular junction 11.

Peripheral to the optical lenticular junction 11 is a pseudotruncation21. Said pseudotruncation 21 comprises a lenticular portion 15, alenticular bevel junction 18, a bevel portion 12, a bevel flangejunction 19, and a flange portion 20. Within said pseudotruncation 21,the lenticular portion 15 surrounds the optical lenticular junction 11.Surrounding the lenticular portion 15 is the lenticular bevel junction18. Further surrounding the lenticular bevel junction 18 is the bevelportion 12. The bevel portion 12 is surrounded by the bevel flangejunction 19 and the flange portion 20. In a preferred embodiment,pseudotruncation 21 is asymmetric about the vertical meridian.

In a preferred embodiment, the pseudotruncation 21, and the distanceoptical zone 14 and near optical zone 13 are tilted nasally up bybetween about 1 to 15°. In a more a preferred embodiment, thepseudotruncation 21, and the distance optical zone 14 and near opticalzone 13 are tilted nasally up by between about 7 to 8°. In anotherpreferred embodiment, the pseudotruncation 21, and the distance opticalzone 14 and near optical zone 13 are tilted nasally up by between about7 to 8°, and both of the optical zones 14, 13 are inset nasally by about0.5 to 1.5 mm. In another embodiment, only the near optical zone 13 isinset nasally by about 0.5 to 1.5 mm.

For convenience, the boundaries of the various zones in all of FIG. 2are shown as discrete lines. However, one ordinarily skilled in the artwill recognize that the boundaries may be blended or aspheric. Theboundaries are smoothed using a scaling function which is generated byspecifying a fixed thickness at two points on the lens and then scalinga smooth surface between said points, the scaling using the sine orcosine taken to a preferred exponential power between about 1.25 andabout 4, with a more preferred value of about 2.

Again referring to FIG. 2, described in a circumferential fashion, thepseudotruncation 21 has a maximum radial thickness between lines 16 and17. Lines 16 and 17 represent the position where the radial thickness isat least about 80% of the maximum thickness. The angle subtended betweenlines 16 an 17 can be between about 40° and about 100°, preferably about60°. In this example, the region of maximum radial thickness is notsymmetric around the vertical meridian 110, and is continuous. Theregion of maximum thickness is rotated 20° counterclockwise from thevertical meridian 110. The width of the bevel portion 12 can be betweenabout 50μ and about 500μ preferably about 100μ. The radial thickness atthe lenticular bevel junction 18 is between about 300μ to 600μ, thepreferred being about between about 450μ to about 475μ. The radialthickness at the bevel flange junction 19 is between about 75μ to 250μ,the preferred being about between about 120μ to about 175μ.

Again referring to FIG. 2, the radial thickness of the lenticularportion 15 is achieved by the use of a mathematical function, with asin² function being preferred. The radial thickness and width of thelenticular portion 15 are variable. The radial thickness at the opticallenticular junction 11 varies with the patient's refractive prescriptionpower. The radial thickness of the bevel portion 12 is achieved by theuse of a mathematical function, with a sin² function being preferred.The radial thickness and width of the bevel portion 12 are variable. Thewidth of the flange portion 20 is variable as defined by the distance ofthe bevel flange junction 19 from the lens center 120. The flangeportion 20 can be described mathematically by a sin² function or itcould be spherical or aspherical. It is preferred that the flangeportion 20 is between about 0.2 to about 1.4 mm in width.

Referring to FIG. 3, lens 10 described in plan view in FIG. 2 is shownas a thickness map. Thicker portions are shaded darker, and thinnerportions are shaded lighter. The pseudotruncation 21 is continuous atit's midpoint 23.

In another preferred embodiment, referring to FIG. 4 lens 10 has ananterior surface, as shown, and a posterior surface, that is not shown.The outermost circumference of lens 10 is symmetrical about the verticalmeridian 110 and lens center 120. Lines 100 and 110 represent thehorizontal, or 0-180 degree, and vertical, or 90-270 degree, meridiansof the lens, respectively. At the intersection of the horizontal 100 andvertical 110 lines is the lens center, 120. On the anterior surface ofthe lens is a distance optical zone 14 and a near optical zone 13, bothending at the optical lenticular junction 11.

Peripheral to the optical lenticular junction 11 is a pseudotruncation21. Said pseudotruncation 21 comprises a lenticular portion 15, alenticular bevel junction 18, a bevel portion 12, a bevel flangejunction 19, and a flange portion 20. Within said pseudotruncation 21,the lenticular portion 15 surrounds the optical lenticular junction 11.Surrounding the lenticular portion 15 is the lenticular bevel junction18. Further surrounding the lenticular bevel junction 18 is the bevelportion 12. The bevel portion 12 is surrounded by the bevel flangejunction 19 and the flange portion 20. In a preferred embodiment,pseudotruncation 21 is asymmetric about the vertical meridian.

In a preferred embodiment, the pseudotruncation 21, and the distanceoptical zone 14 and near optical zone 13 are tilted nasally up bybetween about 1 to 15°. In a more a preferred embodiment, thepseudotruncation 21, and the distance optical zone 14 and near opticalzone 13 are tilted nasally up by between about 7 to 8°. In anotherpreferred embodiment, the pseudotruncation 21, and the distance opticalzone 14 and near optical zone 13 are tilted nasally up by between about7 to 8°, and both of the optical zones 14, 13 are inset nasally by about0.5 to 1.5 mm. In another embodiment, only the near optical zone 13 isinset nasally by about 0.5 to 1.5 mm.

For convenience, the boundaries of the various zones in all FIG. 4 areshown as discrete lines. However, one ordinarily skilled in the art willrecognize that the boundaries may be blended or aspheric. The boundariesare smoothed using a scaling function which is generated by specifying afixed thickness at two points on the lens and then scaling a smoothsurface between said points, the scaling using the sine or cosine takento a preferred exponential power between about 1.25 and about 4, with amore preferred value of about 2.

Again referring to FIG. 4, described in a circumferential fashion, thepseudotruncation 21 has a maximum radial thickness between lines 16 and17. Lines 16 and 17 represent the position where the radial thickness isat least about 80% of the maximum thickness. The angle subtended betweenlines 16 an 17 can be between about 40° and about 100°, preferably about60°. In this example, the region of maximum radial thickness is notsymmetric around the vertical meridian 110, and is continuous. Theregion of maximum thickness is rotated 20° counterclockwise from thevertical meridian 110. The width of the bevel portion 12 can be betweenabout 50μ and about 500μ preferably about 100μ. The radial thickness atthe lenticular bevel junction 18 is between about 300μ to 600μ, thepreferred being about between about 450μ to about 475μ. The radialthickness at the bevel flange junction 19 is between about 75μ to 250μ,the preferred being about between about 120μ to about 175μ.

Again referring to FIG. 4, the radial thickness of the lenticularportion 15 is achieved by the use of a mathematical function, with asin² function being preferred. The radial thickness and width of thelenticular portion 15 are variable. The radial thickness at the opticallenticular junction 11 varies with the patient's refractive prescriptionpower. The radial thickness of the bevel portion 12 is achieved by theuse of a mathematical function, with a sin² function being preferred.The radial thickness and width of the bevel portion 12 are variable. Thewidth of the flange portion 20 is variable as defined by the distance ofthe bevel flange junction 19 from the lens center 120. The flangeportion 20 can be described mathematically by a sin² function or itcould be spherical or aspherical. It is preferred that the flangeportion 20 is between about 0.2 to about 1.4 mm in width.

Referring to FIG. 5, lens 10 described in plan view in FIG. 4 is shownas a thickness map. Thicker portions are shaded darker, and thinnerportions are shaded lighter. The pseudotruncation 21 is not continuousat its' midpoint 23, and transition zone 21 is broken into multiplepieces.

In another preferred embodiment, referring to FIG. 6 lens 10 has ananterior surface, as shown, and a posterior surface, that is not shown.Lines 100 and 110 represent the horizontal, or 0-180 degree, andvertical, or 90-270 degree, meridians of the lens, respectively. At theintersection of the horizontal 100 and vertical 110 lines is the lenscenter, 120. The outer circumference of the lens 10 is not circular, andnot concentric about the lens center 120, the whole lens 10 asymmetricabout the vertical meridian 110. In a preferred embodiment, lens 10 issymmetric about the vertical meridian 110 for portions of said lensabove the horizontal meridian 100; and asymmetric for portions of thelens below said horizontal meridian 100. On the anterior surface of thelens is a distance optical zone 14 and a near optical zone 13, bothending at the optical lenticular junction 11.

Peripheral to the optical lenticular junction 11 is a pseudotruncation21. Said pseudotruncation 21 comprises a lenticular portion 15, alenticular bevel junction 18, a bevel portion 12, a bevel flangejunction 19, and a flange portion 20. Within said pseudotruncation 21,the lenticular portion 15 surrounds the optical lenticular junction 11.Surrounding the lenticular portion 15 is the lenticular bevel junction18. Further surrounding the lenticular bevel junction 18 is the bevelportion 12. The bevel portion 12 is surrounded by the bevel flangejunction 19 and the flange portion 20. In a preferred embodiment,pseudotruncation 21 is asymmetric about the vertical meridian.

In a preferred embodiment, the pseudotruncation 21, and the distanceoptical zone 14 and near optical zone 13 are tilted nasally up bybetween about 1 to 15°. In a more a preferred embodiment, thepseudotruncation 21, and the distance optical zone 14 and near opticalzone 13 are tilted nasally up by between about 7 to 8°. In anotherpreferred embodiment, the pseudotruncation 21, and the distance opticalzone 14 and near optical zone 13 are tilted nasally up by between about7 to 8°, and both of the optical zones 14, 13 are inset nasally by about0.5 to 1.5 mm. In another embodiment, only the near optical zone 13 isinset nasally by about 0.5 to 1.5 mm.

For convenience, the boundaries of the various zones in all of thefigures are shown as discrete lines. However, one ordinarily skilled inthe art will recognize that the boundaries may be blended or aspheric.The boundaries are smoothed using a scaling function which is generatedby specifying a fixed thickness at two points on the lens and thenscaling a smooth surface between said points, the scaling using the sineor cosine taken to a preferred exponential power between about 1.25 andabout 4, with a more preferred value of about 2.

Again referring to FIG. 6, described in a circumferential fashion, thepseudotruncation 21 has a maximum radial thickness between lines 16 and17. Lines 16 and 17 represent the position where the radial thickness isat least about 80% of the maximum thickness. The angle subtended betweenlines 16 an 17 can be between about 40° and about 100°, preferably about60°. In this example, the region of maximum radial thickness is notsymmetric around the vertical meridian 110, and is continuous. Theregion of maximum thickness is rotated 20° counterclockwise from thevertical meridian 110. The width of the bevel portion 12 can be betweenabout 50μ and about 500μ, preferably about 100μ. The radial thickness atthe lenticular bevel junction 18 is between about 300μ to 600μ, thepreferred being about between about 450μ to about 475μ. The radialthickness at the bevel flange junction 19 is between about 75μ to 250μ,the preferred being about between about 120μ to about 175μ.

Again referring to FIG. 6, the radial thickness of the lenticularportion 15 is achieved by the use of a mathematical function, with asin² function being preferred. The radial thickness and width of thelenticular portion 15 are variable. The radial thickness at the opticallenticular junction 11 varies with the patient's refractive prescriptionpower. The radial thickness of the bevel portion 12 is achieved by theuse of a mathematical function, with a sin² function being preferred.The radial thickness and width of the bevel portion 12 are variable. Thewidth of the flange portion 20 is variable as defined by the distance ofthe bevel flange junction 19 from the lens center 120. The flangeportion 20 can be described mathematically by a sin² function or itcould be spherical or aspherical. It is preferred that the flangeportion 20 is between about 0.2 to about 1.4 mm in width.

Referring to FIG. 7, a cross section along the inferior portion of thelens 10, from the lens center through the thickest section of thepseudotruncation 21 of a lens according to FIG. 1 is shown. Theinnermost zone shown is the near optical zone 13, which ends at theoptical lenticular junction 11. Outside of the optical lenticularjunction 11 is the lenticular portion 15. Surrounding the lenticularportion 15 is the lenticular bevel junction 18. Further surrounding thelenticular bevel junction 18 is the bevel portion 12. The bevel portion12 is surrounded by the bevel flange junction 19 and the flange portion20. An arbitrary thickness is found at 22. The pseudotruncation 21 for alens according to this invention is constructed with a lenticularportion 15, a lenticular bevel junction 18, a bevel portion 12, a bevelflange junction 19, and a flange portion 20.

Again referring to FIG. 7, the thickness of the lens is described byscaling a mathematical smoothing function in order to accomplish asmooth and continuous change in thickness on the surface of lens 10.While many such functions are known in the art, using a scaling based onthe sine has been found to be optimal, as it has the advantage of nothaving abrupt changes in slope, and that at its' midpoint, it has avalue of 0.5. By contrast, using a straight line to join the twosegments will also produce a midpoint value of 0.5, it will exhibitabrupt junctions at the two outermost end points. The scaling values arederived from the sine function in the first quadrant, however it isrecognized that the values of the cosine in the fourth quadrant may alsobe used.

In the present invention, again referring to FIG. 7, scaling using thesin² function is accomplished by defining the desired thickness of thelens at several fixed points, and calculating the thickness of thesurface at any point between them. In one example, the thickness at theoptical lenticular junction 11 is fixed at 137μ while the thickness atthe lenticular bevel junction 18 is fixed at 460μ. This can be shown inEquation 1 where P1 is the distance from the lens center to opticallenticular junction 11 and T1 is the thickness at optical lenticularjunction 11. Similarly, P2 is the distance from the lens center tolenticular bevel junction 18 and T2 is the thickness at lenticularjunction 18. P3 and T3 are the arbitrary distance from the lens centerand thickness at this position 22.T ₃ =T ₁+(T ₂ −T ₁)*(Sin((P ₃ −P ₁)/(P ₂ −P ₁)*90))^(n)  Equation 1]

The preferred value of n is between about 1.25 and about 4. The morepreferred value of n is between about 1.5 and about 2.5. The mostpreferred value of n is 2. While this example describes the smooththickness change radially from the center of lens 10, it should beappreciated by those skilled in the art that it could be used todescribe the thickness and thickness change in a circumferentialfashion.

In one preferred embodiment of the invention, the pseudotruncation 21 issubstantially below the horizontal meridian 100 of the lens. In anotherpreferred embodiment of the invention, the pseudotruncation 21 iscomprised of more than one elevated zone. In yet another preferredembodiment of the invention, the pseudotruncation 21 varies in height orcircumferential angular subtense on a basis of data from an individualwearer. In yet another preferred embodiment of the invention, the radialposition of the peak thickness value of the pseudotruncation 21 at anymeridian around the lens is substantially constant, the arc being aportion of a concentric circle about the lens center. In yet anotherpreferred embodiment of the invention, the radial position of the peakthickness value of the pseudotruncation 21 at any meridian around thelens is variable, the arc not being a portion of a concentric circleabout the lens center. In yet another preferred embodiment of theinvention, the outer circumference of the lens 10 is substantiallycircular, or concentric with a constant radius about the lens center120. In yet another preferred embodiment of the invention, the outercircumference of the lens 10 is not circular, and not concentric aboutthe lens center 120.

In a preferred embodiment of the invention, the slope, width and heightparameters of the pseudotruncation 21 can be determined from populationaverages. In another preferred embodiment, the slope, width and heightparameters of the pseudotruncation 21 can be determined from data froman individual wearer. In another preferred embodiment, the slope, widthand height parameters of the pseudotruncation 21 can be determined fromrefractive prescription data.

The one or more optical zones 13, 14, of the lenses are generallysurrounded by non-optical, lenticular zones. The optical zones 13. 14,have at least one near and one distance vision zones as described, forexample, in U.S. Pat. No. 7,503,652 incorporated by reference herein inits entirety. Many different shapes of vision zones are possible. Opticscan be bifocal, trifocal or have even more vision zones. Optical zonescan be circular or non circular in shape; arcuate, straight line,multiple concentric, radially varying concentric, progressively changingpower functions, and geometric inset segments.

The optical zone of at least one of the anterior and posterior surfacesof a multi-focal translating contact lens according to this inventioncan include a distant vision zone, an intermediate vision zone, and anear vision zone. The multi-focal translating contact lens can providedistant vision correction at a primary gaze (e.g. driving), intermediatevision correction at a half-down-gaze (e.g. work on computer) and nearvision correction at full-down-gaze (e.g. read books and newspaper).

In one embodiment, the intermediate vision zone in a multi-focaltranslating lens of the invention is a progressive power zone, which hasan optical power that continuously changes from the distant vision tothe near vision. Effective use of a trifocal translating contact lens ora multi-focal translating contact lens having a progressive power zonerequires varying amounts of translation across the surface of the eyewhen the eye changes from gazing at an object at a distance (primarygaze) to gazing at an object at an intermediate distance (partially-downor half-down gaze) or to gazing at a nearby object (fully-down gaze).This is controlled by the presence of the pseudotruncation.

The lenses of the invention can optionally include features to orientthe lens for stabilization. These are in addition to thepseudotruncation and serve to make sure that the pseudotruncation is onthe bottom of the lens, adjacent to the lower eyelid when worn.Stabilization or orientation features include stabilization zones, prismballast, slab off, dynamic stabilization and the like.

The contact lenses of the invention may be either hard or soft lenses,but preferably are soft contact lenses. Soft contact lenses, made of anymaterial suitable for producing such lenses, preferably are used.Suitable preferred materials for forming soft contact lenses using themethod of the invention include, without limitation, siliconeelastomers, silicone-containing macromers including, without limitation,those disclosed in U.S. Pat. Nos. 5,371,147, 5,314,960, and 5,057,578incorporated in their entireties herein by reference, hydrogels,silicone-containing hydrogels, and the like and combinations thereof.More preferably, the lens material contains a siloxane functionality,including, without limitation, polydimethyl siloxane macromers,methacryloxypropyl polyalkyl siloxanes, and mixtures thereof, a siliconehydrogel or a hydrogel, made of monomers containing hydroxy groups,carboxyl groups, or combinations thereof. Materials for making softcontact lenses are well known and commercially available. Preferably,the material is senofilcon, narafilon, acquafilcon, etafilcon,genfilcon, lenefilcon, balafilcon, or lotrafilcon.

The lenses of the invention may have any of a variety of correctiveoptical characteristics incorporated onto the surfaces in addition todistance and near optical powers, such as, for example, cylinder powerfor the correction of astigmatism, or prism power for the correction oforthoptic or ocular motility problems.

The invention may be further clarified by a consideration of thefollowing examples.

EXAMPLES Example 1 Prophetic

A senofilcon lens in accordance with FIG. 2 is provided. Again referringto FIG. 2, the pseudotruncation 21 has a maximum radial thickness wherethe radial thickness is about 80% of the maximum thickness of about 462microns. In this example, the region of maximum radial thickness issymmetric around the vertical meridian 110, and is continuous. Takenalong the meridian from the lens center 120 where the thickness of thelenticular bevel is a maximum, the width of the lenticular portion 15 isabout 2.625 mm, the width of the bevel portion 12 is about 0.40 mm, andthe width of the flange portion 20 is about 0.20 mm. The radialthickness at the lenticular bevel junction 18 is 460μ. The radialthickness at the bevel flange junction 19 is between about 120μ to 289μ.The radial thickness of the lenticular portion 15 is achieved by the useof a sin² function. The radial thickness of the bevel portion 12 isachieved by the use of a sin² function. The flange portion 20 isdescribed mathematically by a sin² function or it could be spherical oraspherical. Lenses according to this example translate on the eye byabout 1 mm, and are comfortable for the wearer.

Example 2 Prophetic

A senofilcon lens in accordance with FIG. 2 is provided. Again referringto FIG. 2, the pseudotruncation 21 has a maximum radial thickness wherethe radial thickness is about 80% of the maximum thickness of about462°. In this example, the region of maximum radial thickness is notsymmetric around the vertical meridian 110, and is continuous. Takenalong the meridian from the lens center 120 where the thickness of thelenticular bevel is maximum, the width of the lenticular portion 15 isabout 1.25 mm, the width of the bevel portion 12 is about 100μ, and thewidth of the flange portion 20 is about 1.4 mm. The radial thickness atthe lenticular bevel junction 18 is 460μ. The radial thickness at thebevel flange junction 19 is between about 120 to 289μ. The radialthickness of the lenticular portion 15 is achieved by the use of a sin²function. The radial thickness of the bevel portion 12 is achieved bythe use of a sin² function. The flange portion 20 is describedmathematically by a sin² function or it could be spherical oraspherical. Lenses according to this example translate on the eye byabout 1 mm, and are comfortable for the wearer.

Example 3 Prophetic

A senofilcon lens in accordance with FIG. 2 is provided. Again referringto FIG. 2, the pseudotruncation 21 has a maximum radial thickness wherethe radial thickness is about 80% of the maximum thickness of about462°. In this example, the region of maximum radial thickness issymmetric around the vertical meridian 110, and is not continuous. Takenalong the meridian from the lens center 120 where the thickness of thelenticular bevel is maximum, the width of the lenticular portion 15 isabout 2.25 mm, the width of the bevel portion 12 is about 200μ, and thewidth of the flange portion 20 is about 0.60 mm. The radial thickness atthe lenticular bevel junction 18 is 460μ. The radial thickness at thebevel flange junction 19 is between about 120 to 289μ. The radialthickness of the lenticular portion 15 is achieved by the use of a sin²function. The radial thickness of the bevel portion 12 is achieved bythe use of a sin² function. The flange portion 20 is describedmathematically by a sin² function or it could be spherical oraspherical. Lenses according to this example translate on the eye byabout 1 mm, and are comfortable for the wearer.

We claim:
 1. A translating presbyopic contact lens comprising an opticalzone, a peripheral zone around the optical zone and a pseudotruncationwhich is asymmetric and rotated at least one of up or down about thevertical meridian, wherein the pseudotruncation comprises an elongated,arcuate thickened portion in the lens, peripheral to the optical zonebut inside of an edge of the lens.
 2. The contact lens of claim 1wherein the pseudotruncation is rotated nasally up by between 1 to 15degrees.
 3. The contact lens of claim 1 wherein the pseudotruncation isrotated nasally up by between about 7 to 8 degrees.
 4. The contact lensof claim 1 wherein the pseudotruncation is rotated nasally down bybetween about 1 to 10 degrees.
 5. The contact lens of claim 1 whereinthe pseudotruncation and optical zone are rotationally alignedsubstantially the same amount.
 6. The contact lens of claim 1 whereinthe pseudotruncation and optical zone are not rotationally alignedsubstantially at the same amount.
 7. The contact lens of claim 1 whereinthe optical zone is inset horizontally nasalward.
 8. The contact lens ofclaim 1 wherein the optical zone is rotated nasally up.
 9. The contactlens of claim 1 wherein the optical zone is inset horizontally nasalwardand rotated nasally up.
 10. The contact lens of claim 1 wherein theoptical zone is inset horizontally nasalward and rotated nasally up andfurther moved up.
 11. The contact lens of claim 1 wherein thepseudotruncation comprises a single elevated zone.
 12. The contact lensof claim 1 wherein the pseudotruncation comprises more than one elevatedzone.
 13. The contact lens of claim 1 wherein the angular subtense ofthe pseudotruncation when it is 80% of its maximum thickness, is between40 and 100 degrees circumferentially around the lens.
 14. The contactlens of claim 1 wherein the pseudotruncation varies in height orcircumferential angular subtense with changes in refractiveprescription.
 15. The contact lens of claim 1 wherein thepseudotruncation varies in height or circumferential angular subtense ona basis of data from an individual wearer.
 16. The contact lens of claim1 wherein the pseudotruncation varies in height or circumferentialangular subtense on a basis of data from a population, sub-population,or group.
 17. The contact lens of claim 1 wherein the radial position ofthe peak thickness value of the pseudotruncation at any meridian aroundthe lens is substantially constant, the arc being a portion of aconcentric circle about the lens center.
 18. The contact lens of claim 1wherein the radial position of the peak thickness value of thepseudotruncation at any meridian around the lens is variable, the arcnot being a portion of a concentric circle about the lens center. 19.The contact lens of claim 1 wherein the outer circumference of the lensis substantially circular, or concentric with a constant radius aboutthe lens center.
 20. The contact lens of claim 1 wherein the outercircumference of the lens is not circular, and not concentric about thelens center.
 21. The contact lens of claim 1 wherein the width of thebevel portion is between about 50.mu. to about 500.mu.
 22. The contactlens of claim 1 wherein the position of the bevel flange junction isbetween about 5 to about 7 mm.
 23. The contact lens of claim 1 whereinthe maximum radial thickness of the lenticular bevel junction is betweenabout 300.mu. to about 600.mu.
 24. The contact lens of claim 1 whereinthe thickness of the bevel flange junction is between about 75.mu. toabout 250.mu.
 25. The contact lens of claim 1 wherein, when said lens isworn on eye, the thickened portion engages with the lower eyelid of thewearer to achieve translation on the eye.